Face masks generally fall into two categories. The first category includes loose-fitting masks designed to protect a patient from infectious particles expelled by the wearer. The second category includes tight-fitting masks, also know as respirators, that are designed to protect the wearer from inhaling particles or toxins in the ambient air by passing inhaled air through a filter. In a medical environment, respirators also protect patients from particles expelled by the wearer.
It is also desirable to protect the wearer's face (and, in particular, the wearer's eyes) from droplets, sprays, or splashes of body liquids such as blood and saliva encountered during surgery, in the emergency room, or in areas with patients in droplet isolation. Masks combined with transparent plastic sheets have been used for this purpose.